Apparatus and methods for heating water with refrigerant from air conditioning system

ABSTRACT

An apparatus for heating water has a tank for storing water and an air conditioning system that defines a refrigerant flow path through which refrigerant flows. The refrigerant flow path passes through the heat exchanger so that refrigerant heat is contributed to the tank. A control system controls operation of the water heating apparatus.

The present application claims the benefit of the filing date ofprovisional U.S. Patent Application No. 61/779,087, filed Mar. 13, 2013,the entire disclosure of which is hereby incorporated herein for allpurposes.

BACKGROUND OF THE PRESENT INVENTION

Various apparatus and methods have been previously proposed forpre-heating water in a water heater tank using refrigerant from airconditioning apparatus such as an air conditioner with a non-reversiblerefrigerant circuit or a heat pump having a reversible refrigerantcircuit. However, such previously proposed apparatus and methods haveoften proven to be undesirably complex and expensive for use in manyapplications.

SUMMARY OF THE INVENTION

An embodiment of an apparatus for heating water according to the presentinvention includes a tank for storing water, and a heater exchanger inthermal communication with the tank and configured to receiverefrigerant and transfer heat therefrom to the tank. An air conditioningsystem has an air handler actuatable to move an air flow through an airflow path into a conditioned space. A refrigerant path has a firstportion that passes through the air flow path and a second portion thatpasses through the heat exchanger. A pump is disposed in the refrigerantpath and is actuatable to move refrigerant through the refrigerant path.A control system is in operative communication with the air handler tocontrol actuation of the air handler and is in operative communicationwith the pump to control actuation of the pump. In a first mode ofoperation, the control system actuates the air handler to move the airflow through the air flow path and actuates the pump to move refrigerantthrough the first portion of the refrigerant path and the second portionof the refrigerant path. In a second mode of operation, the controlsystem maintains the air handler in an inactive state and actuates thepump to move refrigerant through the first portion of the refrigerantpath and the second portion of the refrigerant path.

In a further embodiment, an apparatus for heating water includes a tankfor storing water and a temperature sensor in thermal communication withwater in the tank and configured to output a first signal correspondingto temperature of the water. A heat exchanger is in thermalcommunication with the tank and is configured to receive refrigerant andtransfer heat therefrom to the tank. An air conditioning system has anair handler actuatable to move an air flow through an air flow path intoa conditioned space. A refrigerant path has a first portion that passesthrough the air flow path and a second portion that passes through theheat exchanger. A valve system within the refrigerant path controlsrefrigerant flow to the first portion and the second portion and isselectively configurable to alternatively allow refrigerant flow throughthe second portion and block refrigerant flow through the secondportion. A pump is disposed in the refrigerant path and is actuatable tomove refrigerant through the refrigerant path. A thermostat is operableto measure ambient temperature in the conditioned space and to output asecond signal corresponding to ambient temperature in the conditionedspace. A control system is in operative communication with the tank toreceive the first signal, is in operative communication with the airhandler to control actuation of the air handler, is in operativecommunication with the pump to control actuation of the pump, is inoperative communication with the valve system to selectively allowrefrigerant flow through the second portion and block refrigerant flowthrough the second portion, and is in operative communication with thethermostat to receive the second signals. In response to the first andsecond signals, in a first mode of operation, the control systemactuates the air handler to move the air flow through the air flow path,actuates the pump to move refrigerant through the refrigerant path, andconfigures the valve system to allow refrigerant flow through the secondportion. In a second mode of operation, the control system maintains theair handler in an inactive state, actuates the pump to move refrigerantthrough the refrigerant path, and configures the valve system to allowrefrigerant flow through the second portion. In a third mode ofoperation, the control system actuates the air handler to move the airflow through the air flow path, actuates the pump to move refrigerantthrough the refrigerant path, and configures the valve system to blockrefrigerant flow through the second portion.

In a further embodiment, an apparatus for heating water has a tank forstoring water and having a heat source. A heat exchanger is in thermalcommunication with the tank and is configured to receive refrigerant andtransfer heat therefrom to the tank. An air conditioning system has anair handler actuatable to move an air flow through an air flow path intoa conditioned space. A refrigerant path has a first portion that passesthrough the air flow path and a second portion that passes through theheat exchanger. A pump is disposed in the refrigerant path and isactuatable to move refrigerant through the refrigerant path. A pluralityof sensors respectively output signals representative of respectivesystem operating parameters. A control system is in operativecommunication with the tank to control operation of the heat source, isin operative communication with the air handler to control actuation ofthe air handler, is in operative communication with the sensors toreceive the respective signals, and is in operative communication withthe refrigerant path to control refrigerant flow. In response to thesignals from the sensors, the control system selectively allows orblocks refrigerant flow through the second portion and selectivelyactuates the water heater heat source.

In a still further embodiment, an apparatus for heating water has a tankfor storing water and having a heat source. A heat exchanger is inthermal communication with the tank and is configured to receiverefrigerant and transfer heat therefrom to the tank. An air conditioningsystem has an air handler actuatable to move an air flow through an airflow path into a conditioned space. A refrigerant path has a firstportion that passes through the air flow path and a second portion thatpasses through the heat exchanger. A pump is disposed in the refrigerantpath and is actuatable to move refrigerant through the refrigerant path.A valve system within the refrigerant path controls refrigerant flow inthe first portion and the second portion and is selectively configurableto alternatively allow refrigerant flow through the second portion andblock refrigerant flow through the second portion. A plurality ofsensors each outputs a respective signal representative of a respectivesystem operating parameter that varies in a predetermined relationshipwith operating efficiency of at least one of the tank and the airconditioning system. A control system is in operative communication withthe tank to control operation of the heat source, is in operativecommunication with the air handler to control actuation of the airhandler, is in operative communication with the sensors to receive therespective signals, and is in operative communication with the valvesystem to control refrigerant flow. In response to the respectivesignals from sensors, the control system selectively actuates the valvesystem to allow refrigerant flow through the second portion or blockrefrigerant flow through the second portion and selectively actuates thewater heater heat source.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present invention can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale. An enabling disclosure of the present invention,including the best mode thereof, is set forth in the specification,which makes reference to the appended drawings, in which:

FIG. 1 is a schematic view of an air conditioning system according to anembodiment of the present invention, with an air conditioning systemproviding only conditioned space air conditioning;

FIG. 2 is a schematic diagram of the system as in FIG. 1, but with theair conditioning system providing conditioned space air and providingrefrigerant heat to a water heater;

FIG. 3 is a schematic diagram of the system as in FIG. 2, but with theair conditioning system providing refrigerant heat to one of two waterheater tanks in a two water heater tank arrangement;

FIG. 4 is a schematic diagram of a an air conditioning system accordingto an embodiment of the present invention, with an air conditioningsystem providing only conditioned space air cooling;

FIG. 5 is a schematic diagram of the system as in FIG. 4, but with theair conditioning system providing conditioned space air and providingrefrigerant heat to a water heater;

FIG. 6 is a schematic diagram of the system as in FIG. 4, but with theair conditioning system providing conditioned space air heating withoutproviding refrigerant heat to a water heater;

FIG. 7 is a schematic diagram of the system as in FIG. 4, but with theair conditioning system providing conditioned space air and providingrefrigerant heat to a water heater;

FIG. 8 is a schematic diagram of an air conditioning system according toan embodiment of the present invention;

FIG. 9 is a schematic diagram of the system as in FIG. 8, but with theair conditioning system providing conditioned space air cooling withoutproviding refrigerant heat to a water heater;

FIG. 10 is a schematic diagram of the system as in FIG. 8, but with theair conditioning system providing conditioned space air heating withoutproviding refrigerant heat to a water heater;

FIG. 11 is a schematic diagram of the system as in FIG. 8, but with theair conditioning system providing conditioned space air and providingrefrigerant heat to a water heater;

FIG. 12 is a schematic diagram of the system as in FIG. 8, but with theair conditioning system providing conditioned space air and providingrefrigerant heat to a water heater; and

FIG. 13 is a schematic diagram of the system as in FIG. 8, but with theair conditioning system providing refrigerant heat to a water heaterwithout providing conditioned space air.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof embodiments of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to presently preferred embodimentsof the invention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation ofthe invention, not limitation of the invention. In fact, it will beapparent to those skilled in the art that modifications and variationscan be made in such examples without departing from the scope or spiritthereof. For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and there equivalents.

As used herein, the terms “air conditioning” apparatus, system, etc.encompass apparatus useable to change the temperature of air beingdelivered to a conditioned space and having an associated refrigerantcircuit. Thus, an “air conditioning” apparatus or system may comprise,without limitation, (1) an air conditioning unit (or “air conditioner”)having a non-reversible refrigerant circuit that may be used to cool airdelivered to a conditioned space, or (2) a heat pump having a reversiblerefrigerant circuit that may be used to heat or cool air delivered to aconditioned space.

Residential and commercial air conditioning systems capture heat at somepoint in the refrigerant's continuous cycle and transfer the heat to apoint inside or outside the building, depending upon whether the systemis functioning in a cooling mode or, if capable of dual modes, in aheating mode. In carrying out principles of one or more embodiments ofthe present invention, a portion of that heat may be captured and usedto heat water in the building's water heater to a temperature at or,more often, below a high set point temperature of the water heater. Anelectric element or gas burner in the water heater may provideadditional heat to bring the water temperature up to the water heater'shigh set point temperature.

An air conditioning/water heater system 10 embodying principles of anembodiment of the present invention is schematically depicted in FIGS. 1and 2 and includes (1) an air conditioning system 12 having an outdoorcondensing coil unit 14 and an indoor evaporating coil unit 16, and (2)an associated water heater 18 which, representatively, may be agas-fired or electric water heater. In FIG. 1, air conditioning system12 is arranged so that it operates in an air cooling mode only, and inFIG. 2 is in an air cooling mode and further provides supplemental,refrigerant-based heat to water heater 18. The various functions of airconditioning/water heater system 10 are controlled by a schematicallydepicted electronic control circuit 20 (shown only in FIG. 1) thatoperates various subsequently described components of the overall system10.

As should be understood, an air conditioning system, from the standpointof refrigerant flow, comprises a closed loop of refrigerant flowingamong a compressor (i.e. a pump), a condenser coil, and an evaporatorcoil. In so-called split systems, one of the two coils is disposedinside the enclosure that is receiving conditioned air (the conditionedspace, e.g. a building interior space), in association with an airhandler, while the other coil is disposed outside the enclosure of theconditioned space, in the ambient environment. The compressor may beinside or outside the enclosure, such as a building interior, but istypically outside in a housing that also encloses the outside coil. In asystem configured only to cool, the outdoor coil is the condenser, andthe indoor coil is an evaporator. Refrigerant flows from the compressor,to the outdoor condenser coil, to the indoor evaporator coil, and backto the compressor. The outdoor unit includes a fan that draws ambientair across the condenser coils to draw heat from the coils. As will beunderstood, the refrigerant acquires this heat in part from the indoorair at the evaporator as the liquid refrigerant evaporates in the coilin response to the influence of an expansion valve at the coil's input.As the system's air handler fan moves the building's recirculating airover the evaporator coils as the refrigerant changes phase from liquidto gas, the refrigerant removes energy (i.e. heat) from the indoor air,thereby cooling the air as it is forced back into the building'sconditioned space. The warm refrigerant gas then flows from theevaporator coil to the compressor, which receives the gas and pumps itback to the condenser, adding pressure and heat. In embodiments in whichthe air conditioning system operates as a heat pump, refrigerant linesbetween the compressor and the condenser, and between the compressor andthe evaporator, pass through a reversing valve so that, when switchingfrom cooling mode to a heating mode, the control system actuates thereversing valve to direct the compressor output to the indoor coil,rather than to the outdoor coil. The roles of the indoor and outdoorcoils reverse from those the coils have in air cooling modes, but thesequence of compressor-condenser-evaporator-compressor remains.

As noted, the condenser cools the refrigerant, thereby dissipating therefrigerant's acquired heat (from the evaporator and the compressor) tothe ambient environment via the air flow that the fan moves over thecoil. The temperature reduction in the condenser also reduces therefrigerant's volume, in turn reducing its pressure, but the refrigerantflow path length and tubing dimensions, and the compressor's size andstrength, are selected so that sufficient positive and negative pressureremain at the condenser's output and input to continue refrigerant flowto the evaporator and therefrom back to the compressor. The selection ofsuch system components and operating parameters to enable desired heattransfer and recirculating refrigerant flow through the flow circuitshould be well understood in this art. While it should be understoodthat the air conditioning systems described below are designed toprovide sufficient heat transfer and pressure to maintain systemoperation, these variables are not discussed further herein.

One or more embodiments of the present invention described herein insertinto the refrigerant path a cooling coil that is proximate a waterheater to be in thermal communication with the water heater tank andthereby transfer heat from the flowing refrigerant to water in the tank.The addition of the cooling coil does not disrupt the air conditioningsystem's underlying compressor-condenser-evaporator-compressor sequence,but it is nonetheless encompassed within the present disclosure to use asingle coil, wrapped around a water heater tank and functioning as boththe heat exchanger and the air conditioning system condenser, inconditions where the heat exchanger provides sufficient cooling for theair conditioning system's condenser needs and where the air conditioningsystem does not require air flow over the condenser. Thus, although thepresent disclosure primarily discusses examples having a fan-drivensystem condenser and a distinct water heater heat transfer coil, itshould be understood that other arrangements fall within the presentdisclosure.

Although the presently-described embodiments are discussed in thecontext of split-type air conditioning systems, it should be understoodthat the present disclosure encompasses air conditioning systems inwhich the condenser and evaporator coils may be located in the samehousing.

Control system 20 may comprise a programmable logic controller (PLC)that operates as the general system controller. Housed, for example,with outdoor unit 14, the PLC communicates with and controls (viasuitable electrical connections, relays, power sources, and otherelectromechanical connections, as should be understood in this art) theactuation and operation of the components described herein, includingbut not limited to the compressor, outdoor coil fan, indoor coil fan,and all electrically controlled valves. As such, the control systemcommunicates with and controls the air conditioning system, includingthe valve system within the refrigerant flow path that, in conjunctionwith the compressor (also controlled by the control system) controlsrefrigerant flow. The reference to connections between control system 20and each of outdoor unit 14, indoor unit 16, and water heater 18 (andbetween control system 70 and each of outdoor unit 64, indoor unit 66,and water heater 68, and between control system 120 and each of outdoorunit 114, indoor unit 116, and water heater 138) encompass suchcommunications and control. Such communication may also encompasscommunication between the control system and a temperature sensor at theoutdoor unit, which provides a signal to the control systemcorresponding to temperatures of the outdoor unit's ambient environment.Furthermore, control system 20 receives input signals from one or morethermostats in the building's conditioned space that provideinstructions regarding whether to activate the air conditioning system,deactivate the air conditioning system, actuate the air handler fan,operate the system in air cooling mode, and (where the air conditioningsystem is a heat pump) operate the system in air heating mode. Thethermostat, being located in the conditioned space and including atemperature sensor, may also output to the control system a signalcorresponding to temperature of the conditioned space. The operation ofthermostats in generating such instructions should be well understoodand is, therefore, not discussed further herein. The thermostat may beconsidered a part of control system 20, and, in any event, functionstypically performed by the thermostat can be shared or performed bycontrol system 20. The reference to communication between controller 20and indoor unit 16 (and between control system 70 and indoor unit 66,and between control system 120 and indoor unit 116) encompass suchcommunications between the control system and the thermostat(s), as wellas communication between the control system and the air handler andbetween the control system and the water heater. The control systemactivates and deactivates the air handler, based on the air conditioningsystem programming in response to signals from the thermostat andpossibly signals from sensors indicating system operating parameters, asshould be understood. In an inactive state, the air handler does notforce air into, draw air into, or otherwise move air through theconditioned space. As discussed herein, actuation of the airconditioning system may refer to activation of the compressor to moverefrigerant through the refrigerant path, activation of the condenserfan, and activation of the air handler (fan), in certain embodiments.But as discussed herein, in some circumstances the air conditioningsystem may be actuated without activating the air handler. In thatsense, the control system activates the air conditioning system whilemaintaining the air handler in an inactive state.

Reference to communication between controller 20/50/120 and indoor unit16/66/116 also encompasses communication between the control system andthe water heater, e.g. the water heater controller or, particularlywhere the water heater controller's functions are incorporated by thecontrol system, between the control system and the water heatertemperature sensor(s) and heat source(s). As should be understood, waterheater 18 may include an electronic controller (not shown) that canreceive manual or electronic instructions to activate and deactivate awater heater and can respond to such instructions as well as activatingand deactivating the water heater in response to pre-programmed setpoint temperatures. The water heater's high and low set pointtemperatures are typically capable of manual or electronic setting bythe operator and/or at installation. Once set, the water heater'scontroller monitors the output of one or more temperature sensors inthermal communication with water inside the water heater and comparesthe water temperature with the predetermined set points. If the waterheater is in an inactive state, and if the water tank temperature isabove the water heater's low set point, the water heater controllertakes no action until the water tank temperature reaches or falls belowthe low set point. At this point, the water heater controller activatesthe water heater's internal heat source, which begins to heat the water.The water heater controller continues to receive and monitor watertemperature signals from the one or more water heater temperaturesensors, and maintains the water heater heat source active until thecontroller receives a signal from the one or more temperature sensorsindicating that the water heater temperature has exceeded the high setpoint. The water heater goes back to an inactive mode and does notreactivate until manually activated or until the signal from the one ormore temperature sensors indicates that the water temperature has againfallen to or below the low set point.

In the presently described embodiments, however, the water heatercontroller passes the water heater temperature sensor signals orcorresponding data to control system 20/70/120, which then determineswhether to heat the water heater with refrigerant heat or with the waterheater's inherent heat source, as described above. If, or when, thecontrol system decides to operate the water heater heat source, thecontrol system sends a corresponding signal to the water heatercontroller, which actuates the heat source. The water heater controllermay thereafter monitor water temperature and deactivate the heat sourcewhen the temperature reaches the high set point, or it may continue topass the temperature signal or data to the control system, which makesthe decision when to deactivate the water heater heat source and sendsan appropriate instruction signal to the water heater controller. Stillfurther, the water heater controller may be omitted, and the controlsystem 20/70/120 put in direct communication with the water heatertemperature sensor(s) and heat source control (i.e. activation anddeactivation control) in order to perform the functions describedherein. The reference to communication between controller 20 and waterheater 18 (and between control system 70 and water heater 68, andbetween control system 120 and water heater 138) encompass suchcommunications between the control system and the water heatercontroller or, particularly where the water heater controller'sfunctions are incorporated by the control system, between the controlsystem and the water heater temperature sensor(s) and heat source(s).

Similarly, as described below, control systems 20 and 70 communicatewith variable fan controllers 25 and 115, and the communicationsindicated between control systems 20 and 70 and outdoor and indoor units14/64 and 16/66 reflect such communications. Still further, however, thefunctions of the variable fan controllers may also be incorporatedentirely within the control system, so that the fan controllers may beomitted and the control system communicates directly with temperaturesensors 27/117, or 42 or 46.

It will be understood from the present disclosure that the functionsascribed to control system 20/70/120 may be embodied bycomputer-executable instructions of a program that executes on one ormore computers, for example embodied by a residential or commercialsplit system air conditioning system controller. Generally, programmodules include routines, programs, components, data structures, etc.,that perform particular tasks and/or implement particular abstract datatypes. Moreover, those skilled in the art will appreciate that thesystems/methods described herein may be practiced with variouscontroller configurations, including programmable logic controllers,simple logic circuits, single-processor or multi-processor systems, aswell as personal computers, hand-held computing devices,microprocessor-based or programmable consumer or industrial electronics,and the like. Aspects of these functions may also be practiced indistributed computing environments, for example in so-called “smarthome” arrangements and systems, where tasks are performed by remoteprocessing devices that are linked through a local or wide areacommunications network to the components otherwise illustrated in theFigures. In a distributed computing environment, programming modules maybe located in both local and remote memory storage devices. Thus,control system 20 may comprise a computing device that communicates withthe system components described herein via hard wire or wireless localor remote networks.

A controller that could effect the functions described herein couldinclude a processing unit, a system memory and a system bus. The systembus couples the system components including, but not limited to, systemmemory to the processing unit. The processing unit can be any of variousavailable programmable devices, including microprocessors, and it is tobe appreciated that dual microprocessors, multi-core and other multiprocessor architectures can be employed as the processing unit.

Software applications may act as an intermediary between users and/orother computers and the basic computer resources of electronic controlsystem 20, as described, in suitable operating environments. Suchsoftware applications include one or both of system and applicationsoftware. System software can include an operating system that acts tocontrol and allocate resources of control system 20. Applicationsoftware takes advantage of the management of resources by systemsoftware through the program models and data stored on system memory.

The controller may also, but does not necessarily, include one or moreinterface components that are communicatively coupled through the busand facilitate interaction with the control system. By way of example,the interface component can be a port (e.g., serial, parallel, PCMCIA,USC, or FireWire) or an interface card, or the like. The interfacecomponent can receive input and provide output (wired or wirelessly).For instance input can be received from devices including but notlimited to a pointing device such as a mouse, track ball, stylus, touchpad, key pad, touch screen display, keyboard, microphone, joy stick,gamepad, satellite dish, scanner, camera, or other component. Output canalso be supplied by control system 20 to output devices via theinterface component. Output devices can include displays (for examplecathode ray tubes, liquid crystal display, light emitting diodes, orplasma) whether touch screen or otherwise, speakers, printers, and othercomponents. In particular, by such means, control system 20 receivedinputs from, and directs outputs to, the various components with whichcontrol system 20 communicates, as described herein.

In general, the control system receives signals from the thermostat, thewater heater, and possibly temperature sensors or other operatingparameter sensors that are not part of the thermostat or water heater.The controller activates or deactivates the air conditioning system toprovide or stop the provision of conditioned air to a conditioned spacein response to the thermostat signals. It decides whether to activate awater heating source in response to the water heating signal, and itdecides which water heating heat source to utilize in response to thewater heater signals and the operating parameter signals (which mayinclude the thermostat signal) and in some instances in response to theair conditioning mode in which the air conditioning system exists. Theapparatus for carrying out these functions, and the manner of theiroperation, are described below.

Referring initially to FIG. 1, outdoor condensing unit 14 includes acondenser coil 22, an associated condenser fan 24, and a compressor 26.The condenser coil and compressor are coupled, as shown, by arefrigerant tubing circuit 28 and liquid refrigerant line portions 30and 32, to indoor unit evaporator coil 34 and to a heat conductiverefrigeration tube spiral-wrapped around a metal tank portion 36 ofwater heater 18 and serving as a refrigerant to tank water heaterexchanger 38 for water heater 18. Although a single coil is illustrated,multiple parallel coils may be utilized to reduce pressure drop throughthe heat exchanger. Thus, it should be understood that reference to aheat exchanger “coil” encompasses one or multiple coils, in series or inparallel. It will also be understood that the coils may be covered ininsulation.

Operatively linked to electronic control system 20 are (1) anelectronically controlled regulator valve 40 with an associatedrefrigerant temperature sensor 42 installed as shown in refrigeranttubing circuit 28 within condensing unit 14, (2) an electronicallycontrolled regulator valve 44 and an associated refrigerant temperaturesensor 46 installed as shown in refrigerant tubing circuit 28 betweenline 32 and (adjacent to) a refrigerant inlet 48 of heat exchanger coil38, and (3) a normally open solenoid valve 50 installed in a refrigerantbypass line 32 a between heat exchanger inlet 48 and a heat exchangerrefrigerant outlet 52. As illustrated in FIG. 1, water to be heatedflows into water heater tank 36 via a water inlet pipe 54 and, inresponse to a heated water demand, is discharged from tank 36 via a hotwater supply pipe 56.

FIGS. 1-7 illustrate temperature sensors 42, 46, 27, 102, and 117. Asdescribed below, temperature sensors 27 and 117 are utilized by fancontrollers 25 and 115, respectively, in variably driving the outdoorand indoor coil fans. Each of temperature sensors 42, 46, and 102illustrate other positions at which temperature sensors may be placed toprovide temperature information to drive control of the outdoor fan, inplace of temperature sensor 27. These sensors should, therefore, beunderstood as alternatives to sensor 27 and may be omitted in thepresence of sensor 27.

Further, the Figures illustrate various electronically controlled valvesas normally open or normally closed valves, whereas other valves areillustrated as electronically controlled proportional valves. As will beunderstood, the normally open or normally closed valves transitionbetween open or closed states, whereas the proportional valves can beused to meter fluid flow if desired. In the examples discussed herein,all the electronically controlled valves transition between fully openand fully closed states, and it is thus encompassed within the presentdisclosure that all valves may be non-proportional valves. It shouldalso be understood, however, that the use of proportional valves tometer fluid flow, for example via the condenser bypass valves, isencompassed within the scope of the present disclosure.

An expansion valve 58 is disposed in line 32 at an inlet to indoor coil34. As should be understood, an expansion valve receives a fluid inputat a high pressure and, depending on the settings within the valve,outputs the fluid at a lower pressure. This allows pressurizedrefrigerant entering coil 34 (when used as an evaporator) to drop inpressure in the evaporator coil and change phase from a liquid to a gas.

Under the conditions illustrated in FIG. 1, control system 20 receives asignal from controller or a temperature sensor in water heater 18indicating that the tank's water temperature is above the water heater'slow set point, which is stored in the control system's memory. That is,no water heating is called for. Assume, also, that control system 20 hasreceived a signal from the building's thermostat (not shown) requiringthe air conditioning system to provide cool air to the conditionedspace. With air conditioning system 12 accordingly in an aircooling-only mode, without need for the control system to also selectand actuate a water heating heat source (e.g. the water heater's heatsource or refrigerant heat transferred to the water in tank 36 via heatexchanger 38), gaseous refrigerant flows from evaporator coil 34 tocompressor 26 via suction line 30. Compressor 26 pumps the gaseousrefrigerant forward, increasing the refrigerant's pressure andtemperature and causing the now-hotter refrigerant gas to flow throughcondenser coil 22. Control system 20 actuates fan 24 (at a constantspeed) via a variable fan speed control 25 to thereby push or draw airover the condenser coils, causing the gaseous refrigerant to cool incoil 22 and thereby change phase from a gas to a liquid. This draws heatenergy from the refrigerant into the moving air, thereby dissipatingheat from the refrigerant (and, therefore, from the conditioned space)into the ambient environment. Still under the pressure provided bycompressor 26, the now-liquid refrigerant flows from the output ofcondenser 22 to the split between the input line to heat exchanger 38and the bypass line including valve 50. Control system 20 maintainsvalve 40, between the condenser and the compressor, closed. Since nowater heating is called for, control system 20 maintains valve 44 closedand valve 50 in its normally fully open position. This blocksrefrigerant flow to the heat exchanger coil, and liquid refrigerantexiting condenser coil 22 therefore flows through open solenoid valve50, bypassing water heater heat exchanger 38, to expansion valve 58.Expansion valve 58 drops the pressure of the liquid refrigerant as itenters evaporator coil 34. Within the evaporator, the refrigeranttransitions to gaseous phase, drawing heat energy from air flowing overcoil 34, which is disposed in the air flow path generated by an airhandler fan (the air flow path is illustrated schematically in FIG. 1 bythe relationship of coil 34 and the illustrated fan). This cools theindoor air being re-circulated by the air handler, thereby cooling theconditioned indoor space. The now-warmer gaseous refrigerant dischargedfrom evaporator coil 34 then returns to compressor 26 via suction line30, and the cycle repeats.

As noted, control system 20 controls the operation of heat exchanger 38in response to receipt of temperature information from a water heatercontroller or from a temperature sensor at tank 36. As should beunderstood, water heater 18 typically operates between low and hightemperature set points. In the presently-described embodiments, controlsystem 20, rather than the water heater's independent control, respondsto water heater water temperature when it falls below the water heater'slow set point, selecting between the water heater's inherent heat sourceand heat exchanger 38 as the means by which to add heat to the waterheater, depending upon which heat source results in higher overallsystem efficiency. The basis for this decision is discussed in moredetail below.

Turning now to FIG. 2, when water heater 18 requires refrigerant heat(as determined by comparison of the value of a temperature signal fromthe non-illustrated temperature sensor in a bottom portion of tank 36 tothe stored water tank low set point), control system 20 (FIG. 1)appropriately positions the various previously described valves 40, 44,and 50 to which it is linked to cause the refrigerant traversing tubingcircuit 28 from the outdoor unit to pass through heat exchanger 38,thereby adding refrigerant heat to water in tank 36, before flowing toevaporator coil 34. When control system 20 detects that heatingresponsibility should shift from the heat exchanger to the water heaterheat source, or that water heater 18 no longer needs refrigerant heat,as described below, it returns air conditioning system 12 to its aircooling-only mode, as discussed with regard to FIG. 1, in which all ofthe refrigerant flow traversing tubing circuit 28 bypasses water heatercoiled tube heat exchanger 38.

More specifically, when the control system receives a signal from thetemperature sensor indicating water heating is needed, when airconditioning system 12 is otherwise in an operative mode to provideconditioned air to a conditioned space, and when the control systeminitially actuates water heating by heat exchanger 38 rather than thewater heater's inherent heat source, control system 20 switches fanspeed controller 25 from full speed (at which fan 24 is operated duringair cooling-only mode) to a variable speed mode (in which fan speedcontroller 25 controls the speed of fan 24 in response to a temperaturesensor 27, as described below), opens valve 44, closes valve 50, andopens valve 40. By opening valve 44 and closing valve 50, the controlsystem directs the entirety of the refrigerant flow through heatexchanger 38. The condenser coil, however, receives only part of therefrigerant flow output from compressor 26. By opening valve 40 andallowing some of the refrigerant flow to bypass the condenser, therefrigerant flowing from condenser 22 and valve 40 to heat exchanger 28contains both cooler liquid and warmer gaseous refrigerant. That is, therefrigerant flow includes hot gaseous refrigerant that, but for bypassvalve 40, would have cooled and condensed in coil 22 but is insteaddiverted to coil 38, which in turn cools the refrigerant, condenses thegaseous refrigerant component of the dual phase refrigerant flow thatreaches the heat exchanger, and transfers the removed heat to waterwithin water heater tank 36. Accordingly, heat exchanger 38 may beconsidered a sub-condenser or sub-cooler of the overall condenser, as itcompletes the condensing function begun by condenser coil 22.

Valve 40, therefore, effectively diverts heat from the compressor outputto the heat exchanger that the condenser would otherwise have removed.The amount of heat that the valve diverts is defined by the balance ofrefrigerant flow between valve 40 and coil 22. This balance is, in turn,defined by the speed of fan 24. The bypass refrigerant flowing throughvalve 40 is warmer than the condensed refrigerant flowing throughcondenser coil 22. As should be understood, the cooler, condensedrefrigerant presents less resistance to flow through the condenser coilthan does the hot gaseous refrigerant through bypass valve 40, eventhough the bypass valve path is much shorter in length. Thus, if valve40 is opened to its fully open state when condenser 22 is operating atits full capacity, most of the refrigerant from compressor 26 will flowthrough the condenser rather than the bypass valve, thereby delivering arelatively low amount of additional, diverted heat to the heatexchanger. To increase the refrigerant flow balance toward bypass valve40, variable fan controller 25 reduces the speed of fan 24 when waterheating is needed. This reduces the rate at which air flows over thecondenser coils, thereby reducing the rate at which refrigerant in thecondenser coil cools and correspondingly increasing the resistance torefrigerant flow. This, in turn, increases refrigerant flow through thebypass valve and increases the heat contributed to the heat exchanger.

At system set up, control system 50 downloads a target temperature tofan controller 25. When, in system operation, controller 25 receives asignal from controller 20 indicating that water heating mode has begun,fan controller 25 ceases full speed fan operation and compares theoutput of temperature sensor 27 to the target temperature. If the sensor27 temperature is above the target temperature, controller 25 increasesthe speed of fan 24, which thereby draws air over (and cools) therefrigerant in the coil at a higher rate, and reduces the amount of hotbypass refrigerant flowing through valve 40. If the sensor 27temperature is below the target temperature, controller 25 decreases thespeed of fan 24, thereby reducing the heat removed from the refrigerant,and increasing its flow resistance, to thereby allow more hot gaseousrefrigerant to bypass the condenser coil. Thus, the target temperaturerepresents the temperature at which the condenser/bypass combinationprovides refrigerant to the heat exchanger. The target temperaturepreferably does not exceed the temperature at which compressor 26outputs gaseous refrigerant or drop below the temperature of water intank 36.

Selection of the target temperature may depend on the configuration ofsystem 12. Heat exchanger 38 cools refrigerant flowing through its coil(toward a lowest temperature equal to the temperature of water in thewater heater tank) but removes heat from the refrigerant at a rateslower than the condenser's heat removal rate. Moreover, the heatexchanger's heat transfer capacity declines as the water heater's watertemperature rises and approaches the refrigerant temperature. If thetarget temperature for refrigerant exiting outdoor unit 14 is too high,the residual heat retained within the refrigerant flow path (due to theheat exchanger's failure to remove the heat) increases flow pathpressure and, therefore, the work done by compressor 26, for nooffsetting heat transfer gain at the water heater or the conditionedair, thereby reducing system efficiency. On the other hand, setting thetarget temperature tool low reduces the heat exchanger's ability totransfer heat to the water heater tank. One way of selecting a targettemperature within these boundaries is to operate the system in apre-installation calibration process, testing the system's efficiencyand heat transfer for various target temperatures within the possibletemperature range and selecting the target temperature that balancesthese considerations to the user's preference. In one embodiment, thetarget temperature is set to the highest temperature from which heatexchanger 38 can successfully bring refrigerant to the tank watertemperature at any point in the tank's water temperature range betweenthe water heater's low and high set points. Since the heat exchanger'sheat transfer capacity is lower at other tank water temperatures,selection of this target results in some residual heat remaining in therefrigerant flow path as the tank's water temperature moves from thismaximum point, but this cost may be acceptable in order to allow theheat exchanger its maximum heat transfer capacity. In a furtherembodiment, control system 20 downloads a range of temperature targetscorresponding to changing water heater temperatures determined atcalibration, and controller 25 continuously updates the targettemperature in response to temperature data from the control system aswater heater water temperature changes. In a still further embodiment,the control system initially downloads a target temperature equal to apredetermined temperature increment above the present tank watertemperature. As tank water temperature rises, the control systemincreases the target temperature, up to the maximum target temperature.The predetermined increment is selected at system configuration and canbe set as desired.

When the control system receives a signal from the water heatertemperature sensor (either directly or through the water heatercontroller) indicating a need for water heating, control system 20 firstdetermines the air conditioning mode (i.e. providing conditioned air tothe conditioned space, or not providing conditioned air to theconditioned space, and if providing conditioned air in embodiments wherethe system both heats and cools, whether in air-heating or air-coolingconfiguration) in which the air conditioning system presently exists. Asdescribed below, control system 20 may have calibrated data sets forsome or all of its air conditioning operation modes that represent acomparison of system efficiency when relying on the refrigerant heatexchanger or, alternatively, on the water heater's inherent heat source.If the control system has no data sets for its present air conditioningmode, it activates the water heater heat source and relies on that heatsource to fully heat the water, without utilization of the heatexchanger. If it does have data sets for the present air conditioningmode, the control system identifies (1) ambient air temperature asdetected from a temperature sensor at outdoor unit 14 that communicateswith the control system, (2) indoor air temperature as detected by theindoor thermostat, and (3) water tank temperature as detected by thetank temperature sensor. The control system applies this input data tothe air-conditioning-mode-dependent data sets which, given the specificoperating parameter values represented by the input data, provide aratio value representing a comparison of system efficiency (at theseparameter values) when relying on the refrigerant heat exchanger and,alternatively, when relying on the water heater's inherent heat source.Based on this comparison, control system 20 selects between the twoheating options, sets the system valves accordingly, and providescorresponding control signals to the water heater. Water heatingcontinues, utilizing the selected heat source, but the control systemrepeatedly monitors these three input variables and correspondinglyre-assesses the efficiency comparison based on the data sets. If thechoice of heat source resulting from these changing variables changesfrom the then-currently active heat source to the other, and if thatcondition persists uninterrupted for some predetermined period of time,e.g. one minute, then the control system deactivates the presentlyactive heat source and activates the other heat source. The controlsystem continues to monitor the variables, and continues to monitor fora change in chosen heat source that persists for the predetermined timeperiod, and changes the heat source if that condition occurs. In thismanner, the choice of heat source can change multiple times, asconditions change, before the water heater reaches its high set point.When the control system detects that the water heater has reached thehigh set point, the control system deactivates the then-active heatsource and does not reactivate either heat source until receiving awater temperature signal indicating the tank's water temperature hasdropped below the water heater's low set point, at which point the cyclerepeats. In a further embodiment, the control system always assumes thatuse of the refrigerant heat exchanger is more efficient at low waterheater temperatures, and so always initially utilizes the heatexchanger.

The data set represents a comparison of system efficiency between twoconditions: (1) air conditioning system and water heater operation whenthe refrigerant heat exchanger is active and the water heater heatsource is inactive, and (2) air conditioning system and water heateroperation when the refrigerant heat exchanger is inactive and the waterheater heat source is active. For each condition, overall systemefficiency may be defined as the system's coefficient of performance, orCOP. The COP may be described as the ratio of heating or cooling energy(BTU/hr or Watts) provided to the conditioned air plus heating energy(BTU/hr or Watts) moved into the water heater water, divided by energy(BTU/hr or Watts) consumed by the air conditioning system and waterheater in providing such energy to the conditioned air and the waterheater water.

As should be understood in this art, the energy input to the water andconditioned air, and energy consumed, may depend on the electrical andmechanical configuration of the air conditioning and water heatingsystem. For a given system, however, this consideration is a constantand can be accommodated in the calibration process as described herein.Relevant parameters that can vary, however, are:

-   -   Selected water heat source, i.e. the refrigerant heat exchanger        or the water heater's inherent heat source;    -   Air conditioning mode, i.e. (1) air cooling, (2) air heating,        or (3) inactive (neither air cooling nor air heating);    -   Outdoor ambient temperature;    -   Water tank water temperature; and    -   Indoor temperature.

To calibrate the system, the air conditioning and water heating system(e.g. as illustrated in FIGS. 1-3, FIGS. 4-7, or FIGS. 8-13) isconstructed and installed in conditions under which the definingvariables can be controlled. The outdoor unit is operatively installedat a location at which it is possible to both operate the outdoor unitand vary the ambient temperature. The indoor unit is installed at alocation separate from the outdoor unit at which it is possible to varythe indoor (conditioned space) ambient temperature. The water heater isdisposed at a location at which the water heater water temperature canbe controlled independently of the outdoor unit and indoor unit ambienttemperatures.

Each system is then calibrated for each possible combination of thefirst two variables. Consider, first, the system described with respectto FIGS. 1-3. As is apparent from the discussion herein, the system doesnot have an air heating mode, and in its inactive mode the system valvesare not configurable to permit use of the refrigerant heat exchanger.Thus, this system can operate selectively between the refrigerant heatexchanger and the water heater heat source only in its air cooling mode.Accordingly, a data set will exist only for the air-cooling mode, andthe system would need efficiency calibration only under the followingtwo conditions:

-   -   Air cooling space conditioning and operation of refrigerant heat        exchanger; and    -   Air cooling space conditioning and operation of water heater        heat source.

Each of the systems described with respect to FIGS. 4-7 and FIGS. 8-13can operate selectively between the refrigerant heat exchanger and thewater heater heat source in any of its three air conditioning modes, andthus can be calibrated under the following six conditions:

-   -   Air cooling space conditioning and operation of refrigerant heat        exchanger;    -   Air cooling space conditioning and operation of water heater        heat source;    -   Air heating space conditioning and operation of refrigerant heat        exchanger;    -   Air heating space conditioning and operation of water heater        heat source;    -   Inactive air conditioning and operation of refrigerant heat        exchanger; and    -   Inactive air conditioning and operation of water heater heat        source.

Assume, then, that a given system is assembled in such a calibrationenvironment, and operated sequentially in each of its possibleconditions as noted above. In each condition, two of the fiveCOP-relevant variables are fixed, and the remaining three variables(outdoor ambient temperature, water tank temperature, and indoor(conditioned space) temperature) can be controlled in the calibrationenvironment. In particular, each variable can be varied over arespective range of values that would be reasonably expected to occur inthe system's use. Given the three variables, and given the respectiveexpected ranges for each, the system is operated in the calibrationenvironment while varying the three variables and measuring orestimating the components of the system's COP. That is, for combinationsof the three variables over their assumed operative ranges, the systemdetermines and records system COP. For a given system, the resultingdata set is stored or otherwise accessible to control system 20/70/120.Accordingly, after completing the calibration process for each of thedual variable (selected water heater heat source/air conditioning mode)configurations for a given system, the control system has, for eachconfiguration, a COP data set from which COP can be defined withknowledge of the values for the three defining variables (outdoorambient air, water tank water temperature, and indoor temperature).

In a given system's operation, the control system always knows thesystem's air conditioning mode, and it receives values for the threedefining variables from corresponding sensors. As noted, a temperaturesensor at the outdoor unit provides outdoor ambient temperature. Thesystem thermostat provides indoor temperature, and the water heatertemperature sensor provides water temperature. Assume, then, that thesystem is operating in one of the three air conditioning modes, and thecontrol system receives a signal from the water heater temperaturesystem indicating a need for water heating. With calibration complete,the control system has a data set for each of the possible operatingconditions, corresponding to selected water heater heat source and airconditioning mode. If the system is operating in one of the airconditioning modes for which a COP data set exists (e.g. any of thethree air conditioning modes for the systems of FIGS. 4-7 and 8-13, butonly air cooling mode for the system of FIGS. 1 and 2), the controlsystem retrieves the two data sets (one for refrigerant heat exchanger,and one for water heater water source) corresponding to that airconditioning mode, detects the actual defining variable values from thecorresponding sensor inputs, and determines the COP value defined by thethree variables for each of the two data sets. If the ratio of the COPfor the system utilizing the refrigerant heat exchanger to the COP forthe system utilizing the water heater heat source is equal to or greaterthan 1.0, the control system activates the refrigerant heat exchanger(i.e. with regard to the embodiment of FIG. 1, opens valve 44, closesvalve 50, opens valve 40, and instructs controller 25 to control fan 24speed to maintain the target refrigerant level) and deactivates thewater heater heat source, else if the ratio is less than 1.0, thecontrol system deactivates the refrigerant heat exchanger and activatesthe water heater heat source. The control system continuously monitorsthe three defining variables. As long as the water heater watertemperature is below the water heater's high set point, the controlsystem repeatedly (e.g. every ten seconds) measures the three variablesand recalculates the ratio. If the ratio changes state (i.e. movesacross the 1.0 threshold, thereby indicating a change in water heaterheat source from the presently activated source) and persists in thechanged state for more than a predetermined period of time, e.g. oneminute, the control system deactivates the presently active water heaterheat source and activates the other water heater heat source. Thecontrol system thereafter continues to repeatedly read the definingvariable values, re-determine the ratio, and change the water heatsource if so indicated by a persistent ratio. This process continuesuntil the water heater temperature reaches the high set point, at whichpoint the control system deactivates both water heater heat sources, andtakes no further water heating action until the water temperature signalindicates that the water heater water temperature has again fallen to orbelow the water heater's low set point, at which point the cyclerepeats.

In a further embodiment, the control system selects the water heaterheat source based on the system COP comparison as described above, butwith the additional qualification that even if the COP comparisoncontinues to favor selection of refrigerant heat exchanger, if thatselection persists continuously for at least a predetermined period oftime, e.g. thirty minutes, the control system will activate the waterheater heat source and deactivate the refrigerant heat exchanger andthereafter allow the water heater heat source to heat the water heaterwater up to the water heater's high set point, without consideration ofcomparative system efficiency. Since the refrigerant heat exchanger istypically unable to bring the water heater to its final high set pointalone, this modification to the process protects against systemdedication to the refrigerant heat exchanger under conditions in whichthe heat exchanger cannot bring the water to the final set point.

It should be understood that variations in the heat source selectionprocess are encompassed by the present disclosure. For example, itshould be understood in view of the present disclosure that use of therefrigerant heat exchanger tends to be more efficient than use of thewater heater heat source when the water heater water temperature is low.At the lower temperatures, the water heater draws more heat from therefrigerant flowing through the heat exchanger than at highertemperatures, thereby lessening the resistance that the heat exchangercoil provides to refrigerant flow and reducing system pressure. As thewater heater water temperature is always at the water heater low setpoint when the control system initiates water heating, in one embodimentthe control system defaults to operation of the refrigerant heatexchanger at cycle initiation, without reference to the COP comparison(assuming data sets exist for the existing air-conditioning mode).Thereafter, the control system continuously monitors the COP comparison,as described above, and switches to the water heater heat source whenthe ratio drops below 1.0 and persists below that level for at least thepredetermined period of time. Also, recognizing the likelihood that,once the COP comparison transitions the heat source to the water heaterheat source, subsequent COP comparison would likely continue to selectthe water heater heat source, then once the control system switches tothe water heater heat source, the control system no longer examines COP,instead maintaining activation of the water heater heat source throughthe end of water heating. In this embodiment, the control system maycontinue to monitor water heater temperature following the switch to thewater heater heat source or, alternatively, relinquish control of thewater heater heating cycle to the water heater controller to completethe cycle, as discussed above.

It will be understood in view of the present disclosure that variousmethodologies may be used to determine the components of the COPcalculations during system calibration. To determine energy actuallymoved into the water heater water, control system 20 may store watertemperature values received from the water heater's temperature sensorover a predetermined period of time, thereby determining actual changein water temperature. Since the control system also knows the volume ofwater in the water heater, the control system can determine thecorresponding BTU/hr and convert that number to Watts.

As should be understood in this art, precise determination of actualenergy moved into or out of the conditioned air involves a determinationof enthalpy change over the predetermined time period. While methods ofmaking such measurements are known, they may also be unavailable orimpractical. However, since the control system can determine whether theair handler fan has been active over the predetermined period of time,and since the control system knows the air handler's capacity, thecontrol system can estimate the volume of air that the air handler hasmoved into the conditioned space. The control system also measures theconditioned space temperature from the thermostat signals, and based onthe temperature change in the conditioned space and the estimated volumeof air moved into the conditioned space within the predetermined periodof time, the control system can estimate BTU/hr over that period, withinan approximately 10% accuracy. Again, the control system can convertthis number to Watts.

In some instances, of course, certain components of the COP calculationdo not exist. For example, where the air conditioning mode is inactive,there is no energy moved into or out of the conditioned space.

The denominator of the COP calculation is the energy consumed by thesystem in contributing the energy represented by the numerator. This, inturn, is the energy used by the compressor, the coil fans, and the waterheater over the predetermined time. Compressor power utilization may bedirectly measured in calibration by a watt meter or by continuouslymeasuring compressor suction pressure, discharge pressure and suctiongas temperature, in view of the compressor's performance curves. Fanpower can be measured by a watt meter but can be estimates or assumedbased on lab testing.

The overall air conditioner/water heater circuit 10 a schematicallyillustrated in FIG. 3 is identical to the system 10 described above withrespect to FIGS. 1 and 2, with the exceptions that (1) an additionalwater heater 18 a, having either electric or gas heating apparatusassociated therewith, but without an associated coiled tuberefrigerant-to-water heat exchanger, is connected in series with thepreviously-described water heater 18 such that water exiting waterheater 18 via pipe 56 flows through the additional water heater 18 a andis then discharged therefrom through a hot water outlet pipe 56 a, and(2) water heater 18 is not provided with electric or gas heat, butreceives only refrigerant heat via its tubing heat exchanger portion 38,thus functioning solely as a water pre-heating device. Water heater 18 amay correspond in capacity to water heater 18 as shown in FIGS. 1 and 2,which is for example a forty to fifty gallon electric or gas waterheater. The water heater 18 of FIG. 3 may be of a larger, smaller, orsimilar capacity.

The configuration shown in FIG. 3 emphasizes the advantages of therefrigerant flow heat exchanger when water tank water temperature islow. The two tank configuration allows hot water to be stored when theair conditioning system 12 is running (in cooling or heating modes)during times when there is little or no demand for hot water, therebyproviding additional low cost hot water capacity during periods of timewhen the demand for hot water is high. It also improves the efficiencyof the air conditioning system compared to the single tank arrangementdescribed above with respect to FIGS. 1 and 2, since water inpre-heating tank 18 (FIG. 3) will usually be at a lower temperature thanwater in the main tank during periods of time when there is littledemand for hot water.

The system does not use a comparison of efficiencies to control when toactuate and de-actuate the water heating heat exchanger 38 shown in FIG.3. Since the refrigerant heat exchanger is not proximate the same waterheater that is heated by the water heater heat source, the efficiencycomparison described above with respect to FIGS. 1 and 2 (and below withrespect to FIGS. 4-7 and 8-13), is not applicable. Rather, water heater18 a heats under its independent heat source, and the air conditioningsystem activates the refrigerant heat exchanger up to a predeterminedset point temperature of the pre-heated tank 18. The set point is set toa level below the temperature of the compressor output temperature, butit is otherwise selectable by the operator. A pre-heating tank may alsobe used with the air conditioning systems described below with respectto FIGS. 4-7 and 8-13.

An air conditioning system 60 embodying one or more principles of thepresent invention is schematically depicted in FIGS. 4-7 and includes(1) a heat pump 62 having an outdoor coil unit 64 and an indoor coilunit 66, and (2) an associated water heater 68 which, representatively,may be a gas-fired or electric water heater. In FIG. 4, heat pump 62 isin an air cooling-only mode. In FIG. 5, heat pump 62 is in an aircooling mode and further provides supplemental, refrigerant-based waterpre-heating to water heater 68. In FIG. 6, heat pump 62 is in an airheating-only mode. In FIG. 7, heat pump 62 is in an air heating mode andfurther provides supplemental, refrigerant-based water pre-heating towater heater 68. The various functions of air conditioning system 60 arecontrolled by a schematically depicted electronic control circuit 70(shown only in FIG. 4) which operates various subsequently describedcomponents of system 60.

As shown in FIGS. 4-7, outdoor coil unit 64 includes a coil 72 andassociated fan 74, and a compressor 76. Coil 72 and compressor 76 arecoupled, as shown, by a refrigerant tubing circuit 78 having lineportions 80 and 82, to indoor unit coil 84 and to a heat conductivecopper tube that is spiral-wrapped around a metal tank portion 86 ofwater heater 68 and serves as a refrigerant-to-tank water heat exchanger88 for water heater 68.

Outdoor unit 64 has a reversing valve 90, an electronically controlledregulator valve 92, an expansion valve 94, and a check valve 93 (whichcan be considered as the expansion valve's inherent check valve)connected as shown in tubing circuit 78 and operatively linked toelectronic control system 70. Indoor coil unit 66 has a normally closedsolenoid valve 98 and a normally closed solenoid valve 100 connectedacross a check valve 109 as shown in tubing circuit 78 and operativelylinked to electronic control system 70. The indoor unit also has anexpansion valve 110, and the valve 100/109/110 assembly can be replacedby a parallel expansion/check valve as indicated at 93/94. Water heater68 has a temperature sensor 102, an electronically controlled regulatorvalve or normally closed solenoid valve 104, a normally open solenoidvalve 106, and a normally closed solenoid valve 108 connected as shownin tubing circuit 78 and operatively linked to electronic control system70.

Turning now to FIG. 4, with air conditioning system 60 in an aircooling-only mode, electronic control system 70 sets the previouslydescribed valve components in tubing circuit 78 in a manner such thatcompressor 76 causes refrigerant discharged therefrom to flow, viatubing portion 80 of tubing circuit 78, sequentially through condensercoil 72 to water heater 68, evaporator coil 84, and back to thecompressor. More specifically, as hot gaseous refrigerant flows out fromcompressor 76 on an output line 91, control system 70 maintains solenoidvalve 92 closed, so that all of the compressor's output refrigerantflows to reversing valve 90. Control system 70 sets reversing value 90to direct the gaseous refrigerant flow from line 91 to tubing portion 80and thereby to condenser coil 72. Since none of the refrigerant bypassesthe condenser coil through valve 92 in this mode, all of the hotrefrigerant from the compressor condenses in coil 72 and flows therefromvia check valve 93 out of this outdoor unit and to the indoor waterheater.

At the water heater, control system 70 maintains solenoid valve 104closed and solenoid valve 106 open, and the refrigerant bypasses heatexchanger 88 through open solenoid valve 106. The liquid refrigerantthen flows through tubing portion 80, through check valve 109 andexpansion valve 110 (the control system maintains solenoid valves 100,98, and 108 closed, and a check valve 111 blocks flow from left to rightin the perspective of FIG. 4) and into evaporator coil 84. As discussedabove, the expansion valve lowers pressure of the liquid refrigerant,allowing the refrigerant to change phase from liquid to gas in theevaporator coil and draw required heat energy from air flowing over coil84 due to the air handler fan, to thereby cool air in the conditionedspace. Also as discussed above, positive and negative pressurecontributed by compressor 76 in the refrigerant tubing line issufficient so that the now-gaseous refrigerant flows back to compressor76 over tubing line 82 through reversing valve 90, which fluidlyconnects input tubing line 82 to a compressor input tubing line 95.

Referring to FIG. 5, when a temperature sensor (not shown) of waterheater 68 sends an output signal to electronic control system 70indicating that the water temperature of water in tank 68 has reached orfallen below the water heater's low set point temperature (as stored inmemory at electronic control system 70), and if the COP comparisonfavors the refrigerant heat exchanger, the control system repositionswater heater regulator valve 104 and normally open solenoid valve 106such that the refrigerant flows through heat exchanger 88 and back intotubing portion 80, thereby adding refrigerant heat to the tank water, toexpansion valve 110. The settings of valves 104, 106, and 92 are thesame as those for valves 44, 50, and 40, as discussed above with respectto FIG. 2. In addition, valves 108 and 100 remain closed, as refrigerantflows through their respective opposing check valves, and valve 98remains closed. Refrigerant flowing through coil 84 changes phase to agas, as discussed above with respect to FIG. 4, and gaseous refrigerantreturns to compressor 76 via tubing 82 and 95.

Although not shown in FIG. 5, fan 74 is controlled by a variable fanspeed controller (see FIG. 2) that is, in turn, responsive to apre-programmed target temperature in water-heating mode to control thespeed of fan 74 so that the refrigerant flowing from coil 72 and bypassvalve 92 maintain the desired target temperature in tubing 80, asdescribed above with regard to the embodiment of FIGS. 1 and 2. Thetarget temperature maybe selected as discussed above.

Similarly to operation of the embodiment discussed above with regard toFIGS. 1 and 2, control system 70 may select the water heating sourcebased on the COP comparison (data sets exist for the air conditioningmodes of this embodiment) or may default to selection of the refrigerantheat exchanger to heat the water heater when the control system receivesa temperature signal from the water heater indicating a need to heatwater. Regardless of the method or of the heat source chosen, thecontrol system thereafter continuously re-assesses the COP comparisonand selects between the two alternative water heating sources basedthereon, as described above.

It should be understood that the control system may change the system'soperation modes between air cooling of the conditioned space and airheating of the conditioned space (or actuation from one mode to theother from start up), or to the inactive mode, based on operator controlof the system or automatically. When the control system enters an airheating mode, and referring now FIG. 6, the control system changesreversing valve 90 so that the refrigerant flowing from the compressorthrough tubing 91 flows through valve 90 to tubing 82 that connects toindoor coil 84. Valve 98 remains closed. Coil 84, receiving the hotgaseous refrigerant from compressor 76, now acts as condenser, coolingthe refrigerant so that it changes phase back to a liquid. Exiting coil84, the liquid refrigerant bypasses expansion valve 110 through itsinternal check valve and flows through now-open solenoid valve 100around check valve 109. Control system 70 maintains valve 106 open andvalves 104 and 108 closed. Since check valve 111 and closed valve 108otherwise block the refrigerant's flow into heat exchanger 88,refrigerant from coil 84 flows through valve 106 and through tubing 80to outdoor unit 64. The control system maintains valve 92 closed. Thus,all refrigerant from the indoor unit flows through expansion valve 94and into outdoor coil 72. Expansion valve 94 (which is bypassed by itsinternal check valve 93 when the system operates in air cooling modes)lowers the refrigerant's pressure, causing coil 72 to act as anevaporator that draws heat from air passing over the coil as a result ofoperation of fan 74. The now-warmer refrigerant flows from coil 72 toexpansion valve 90, which directs the refrigerant flow to thecompressor's input tubing line 95.

Referring now to FIG. 7, if the electronic control system 70 receives asignal from the temperature sensor at water tank 86 indicating that thetank's water temperature has reached or fallen below the water heater'slow set point while system 60 is operating in an air heating mode,control system 70 decides whether to activate the heat exchanger or thewater heater heat source, e.g., based on the data sets/COP comparison asdescribed above, or by default to the heat exchanger followed by thedata sets/COP comparison. Assuming the control system initiallyactivates the heat exchanger, the control system appropriately adjustsvalves 104, 106, and 108 in a manner such that the refrigerant flow towater heater 68 flows through coiled tubing heat exchanger 88. Morespecifically, control system 70 closes valve 106 and valve 92 and opensvalves 104, 108, 100, and 98.

As discussed above, indoor unit 66 includes an air handling unit havinga fan that draws air over coil 84. As indicated in FIG. 7, unit 66 alsoincludes a variable speed fan control unit 115 in communication withcontrol system 70 and a temperature sensor 117 that detects refrigeranttemperature in the flow of refrigerant combined from the output of coil84 and bypass valve 98. As in the air cooling/water heating mode, whenthe system is in air heating/water heating mode, heat exchanger coil 88acts as a sub-cooling or sub-condensing coil, sharing the condensingfunction with the system condenser, the difference between the two modesof operation being that in air heating mode, coil 84, rather than coil72, is the system condenser. As in the air cooling/water heating mode,the system in air heating/water heating mode diverts some of the hotgaseous refrigerant from compressor 76 to coil 88, bypassing thecondensing coil, in order to contribute heat to the heat exchanger. Andas in the air cooling mode, this is accomplished in the air heating modeby a valve that bypasses the condenser coil, in this instance valve 98.That is, valve 98 serves the function in air heating/water heating modethat valve 92 serves in air cooling/water heating mode.

As discussed above with regard to valve 92 in the air cooling/waterheating mode, the opening of valve 98 in air heating/water heating modeallows hot gaseous refrigerant to flow through the bypass path, butbecause refrigerant flowing through condenser coil 84 is cooled, andthus has lower flow resistance than the hot refrigerant, morerefrigerant tends to flow through the condenser coil than through thebypass when the air handler fan is operating at its normal speed.Accordingly, when control system 70 actuates system 60 to operate in airheating/water heating mode, the control system instructs variable fanspeed controller 115 to variably control the air handler fan speed inresponse to temperature of the combined refrigerant flow detected at 117to maintain the refrigerant flow at 117 at a target temperature that ispre-programmed to controller 115 and/or control system 70. The targettemperature in air-heating mode may be selected independently of theair-cooling mode target temperature, as system conditions can bedifferent. Thus, while the system actuates refrigerant heat exchanger88, the air handler fan generally slows in speed, thereby increasingresistance to refrigerant flow through the condenser coil and forcingmore refrigerant through bypass valve 98. The bypass refrigerant remainsin a hot, gaseous state so that the combination of gaseous refrigerantfrom valve 98 and liquid refrigerant from coil 84 is in a dual-phasestate as it flows to heat exchanger 88.

This refrigerant flows through open valve 108, around check valve 111,and through heat exchanger coil 88. This transfers heat from therefrigerant to the water tank and completes the condensing process, sothat the refrigerant leaving coil 88 through open valve 104 is in afully liquid state. The liquid refrigerant continues its flow throughtubing 80 and valve 94, around check valve 93, to evaporator coil 72.From the evaporator coil, warmer, gaseous refrigerant flows throughtubing 80, reversing valve 90, and input tubing 95 to compressor 76, andthe cycle repeats.

Control system 70 makes the COP comparison as described above todetermine when to alternatively operate refrigerant heat exchanger 88 orthe water heater heat source. As when the system is operating in aircooling mode, the use of refrigerant heat exchanger 88 in air heatingmode will generally be more efficient when the water in tank 86 is at alower temperature. Thus, when control system 70 receives a signal fromthe water heater temperature sensor that the water heater is at or belowits low set point temperature, control system 70 may default tooperation of refrigerant heat exchanger 88 and thereafter continuouslyexamines the efficiency comparison to determine when to switch to thewater heater's operation. Again, since the target temperature to whichfan controller 17 controls the refrigerant input to the heat exchangeris typically below the water heater's high set point temperature, thistypically means that the refrigerant flow heat exchanger acts as apre-heater and that final heating is effected by the water heater heatsource.

It should also be recognized, in view of the present disclosure, thatthe reduction in the air handler fan speed during operation ofrefrigerant heat exchanger 88 corresponds to a reduction of heatprovided to the conditioned space, thereby corresponding to a reductionin system efficiency. When the system operates in air cooling/waterheating mode, the system does not experience a similar efficiencyreduction, in that because conditioned air is delivered to theconditioned space from the evaporator coil rather than from thecondenser coil, energy contribution to the conditioned air is relativelyunaffected by the refrigerant bypass around the condenser. As apparentfrom the discussion above, control system 70 may therefore switch fromuse of heat exchanger 88 to the use of the water heater's heat sourceearlier in air heating/water heating mode than in air cooling/waterheating mode.

In a still further embodiment, variable speed fan controller 115 andsensor 117 may be omitted from the system, and the air handler fan mayoperate at normal speed during actuation of heat exchanger 88 in airheating mode. This avoids the reduction in system efficiency caused bydecrease in fan speed, although because of the resulting reduction indiversion of hot refrigerant to the heat exchanger through valve 98, theheat exchanger would correspondingly contribute less heat to the waterheater, thereby reducing system efficiency. It will therefore beappreciated that the decision whether to utilize variable fan speed, andif so, also the selection of the target refrigerant temperature at theoutput of the bypass valve and the condenser coil, will influence systemefficiency and, therefore, the balance between use of refrigerant heatexchanger 88 and the water heater heat source. It will also beunderstood that, in both air heating and air conditioning modes,decisions regarding use of fan reduction can be made, and operatingparameter values optimized, through calibration of the particular airconditioning system.

In the discussion of the above-described embodiments, the control systemactuates the refrigerant heat exchanger when the air conditioning systemis operating either in an air cooling mode or an air heating mode. Incertain embodiments, the control system only actuates the heat exchangerduring an active mode of the air conditioning system, but in otherembodiments the control system also actuates the refrigerant heatexchanger when the system is in an inactive mode, i.e. when runningneither in air cooling mode nor air heating mode. In such embodiments,and referring for example to the system of FIGS. 4-7, if control system70 receives a signal from the water heater temperature sensor indicatingthat water in the water heater has reached or fallen below the heater'slow temperature set point, the control system decides whether toactivate the heat exchanger or the water heater heat source, e.g., basedon the COP comparison as described above, or by default to the heatexchanger. Assuming the decision is to activate the heat exchanger, thecontrol system arranges the valves in the air conditioning system so asto operate in air heating/water heating mode, as discussed above withrespect to FIG. 7, and operates the air conditioning system in themanner described above with regard to FIG. 7, except that the controlsystem deactivates the air handler fan so that no air is drawn acrosscoil 84 and no conditioned air is provided to the conditioned space.Correspondingly, the variable fan speed controller is inoperative. Thistends to force a greater volume of hot refrigerant from the compressorthrough bypass valve 98, but the refrigerant flow is thereafter the sameas discussed above with regard to FIG. 7. The control system doesoperate fan 24, since the evaporator function is needed to complete therefrigerant cycle. Since the evaporator function is needed, the controlsystem does not select an air cooling set up, as such arrangement wouldcause conditioned air to be forced into the conditioned space.

In this water heating-only mode of operation, the reduced condensercapacity causes the air conditioning system to remove less heat from therefrigerant between the compressor and the evaporator than in the airconditioning modes. The increased refrigerant heat corresponds toincreased flow resistance in the refrigerant circuit and, therefore, toincreased compressor discharge pressure. Depending on the systemconfiguration, this may, in turn, so decrease system efficiency orpossibly inhibit the compressor's operation that use of the refrigerantflow heat exchanger does not occur or occurs for only a short time.Thus, in embodiments utilizing a water heating-only mode, compressor 76may be a variable speed compressor so that control system 70 may reducecompressor speed when heating water with the heat exchanger but notconditioning air. For example, typical residential air conditioningsystems have compressors ranging in capacity from 16,000 to 60,000BTU/hr. In a non-air conditioning mode with water heating, however,control system 70 would lower a variable speed compressor to operate ata lower capacity, e.g. approximately 10,000 BTU/hr in a typicalresidential configuration. As in the air conditioning/water heatingoperational modes discussed above, control system 70 in a waterheating-only mode again determines whether and when to switch betweenheating water with the refrigerant heat exchanger and heating water withthe water heater heat source based on the COP comparison.

In the embodiments described above, the refrigerant heat exchanger coilis disposed downstream of the system condenser. In the embodimentsdiscussed below with respect to FIGS. 8-13, however, the heat exchangercoil is disposed upstream from the system condenser, between the systemcondenser and the compressor. In these embodiments, the heat exchangercoil reduces heat of the hot gaseous refrigerant output by thecompressor (and transfers this heat to the water heater), but it doesnot condense the refrigerant to a liquid phase. Because the heatexchanger coil receives hot refrigerant directly from the compressor, itis unnecessary to bypass the compressor output around the condenser or,therefore, to reduce condenser fan speed in order to encourage suchbypass flow. That is, the system condenser fan operates at normal speedwhether or not the refrigerant heat exchanger is active. This tends toincrease system efficiency as compared to the embodiments describedabove with regard to FIGS. 1-7. In certain environments, however, theembodiments described with regard to FIGS. 1-7 may be more convenient toinstall, particularly into an existing air conditioning system as aretrofit.

FIG. 8 schematically depicts an air conditioning/water heater system 110embodying principles of an embodiment of the present invention. System110 includes (1) an air conditioning system 112 having an outdoor coilunit 114 and an indoor coil unit 116, and (2) and associated waterheater 118 which, representatively, may be a gas-fired or electric waterheater. In FIG. 8, air conditioning system 112 is arranged so that itmay operate alternatively in air heating and air cooling modes, and maytherefore also be described as a heat pump. The various functions of theair conditioning/water heater system 110 are controlled by aschematically depicted electronic control circuit 120 (shown only inFIG. 8) that operates various subsequently described components ofoverall system 110.

Outdoor unit 114 includes an outdoor coil 122 and associated fan 137 anda compressor 126. Condenser coil 122 and compressor 126 are coupled, asshown, by a refrigerant tubing circuit having a line portion 130 betweencoil 122 and a reversing valve 140 through an indoor unit coil 134 andexpansion valve 160, a line portion 131 between reversing valve 140 andcompressor 126 via a heat conductive copper tube that is spiral-wrappedaround a metal tank portion 136 of water heater 118 and serving as arefrigerant-to-tank water heat exchanger 138 for water heater 118, and aline portion 132 between reversing valve 140 and each of coil 122 andcompressor 126.

In addition to reversing valve 190, outdoor unit 114 includes anelectronically controlled regulator valve 142, an expansion valve 153 atan input to outdoor coil 122 (bypassed when receiving outflow from coil122), solenoid valves 144 and 154, and a check valve 161. Valves 154,144, 142, and 140 are in electrical communication with electroniccontrol system 120, which controls the actuation of these valves asdiscussed herein.

Turning now to FIG. 9, with the air conditioning/water heater system 110in an air cooling only mode, electronic control system 120 (FIG. 8) setsvalves 154, 144, and 140 in the overall tubing circuit in a manner suchthat compressor 126 causes refrigerant discharged therefrom to flow, viatubing portion 131, to the entry point of a tubing loop that includesheat exchanger 138 wrapped around tank 136 of water heater 118.Electronic control system 120 has closed valve 154 and opened valve 144,so that hot gaseous refrigerant flowing from compressor 126 bypassesheat exchanger 138 and flows directly to reversing valve 140. Controlsystem 120 has set reversing valve 140 so that the reversing valvedirects this refrigerant flow, via tubing line 132, to outdoor coil 122,which condenses the refrigerant in cooperation with fan 137 as discussedabove. The refrigerant exits coil 122 via tubing line 130 (bypassingexpansion valve 163) and enters indoor coil 134 via expansion valve 160.As discussed above, and as should be understood, expansion valve 160lowers the pressure of the refrigerant in coil 134 so that coil 134functions as an evaporator. An air handler fan 135 adjacent coil 134causes air to flow over coil 134 and into the conditioned space. Asdiscussed above, the refrigerant's change of phase in the evaporatorcoil from liquid to gas draws heat energy from this air, thereby causingthe re-circulating air to cool the conditioned space. The now gaseousand warmer refrigerant flows from coil 134 via tubing portion 130 toreversing valve 140, which directs the gaseous refrigerant flow, viatubing portion 132, back to compressor 126, and the cycle repeats.

Referring to FIG. 11, when the system is operating in air cooling modeas described above with regard to FIG. 9, and when a temperature sensor(not shown) of water heater 118 outputs a signal to electronic controlsystem 120 indicating to the electronic control system that the waterheater water has reached or fallen below the water heater's low setpoint temperature as stored in the electronic control system, thecontrol system decides whether to activate the heat exchanger or thewater heater heat source, e.g., based on the COP comparison as describedabove or by default to the heat exchanger. Assuming the decision is toactivate the heat exchanger, the electronic control system closes valve144 and opens valve 154, thereby activating refrigerant heat exchanger138. Reversing valve 140 remains in the same setting as discussed withregard to FIG. 9. Under these conditions, hot gaseous refrigerant outputfrom compressor 126 flows to heat exchanger 138 of water heater 118 viatubing portion 131, bypassing valve 144, and ultimately to reversingvalve 140 via check valve 161. The refrigerant flows from the reversingvalve to outdoor condenser coil 122, and then to expansion valve 160,indoor coil 134, reversing valve 140, and back to compressor 126, asdiscussed above with respect to FIG. 9.

Once the electronic control system actuates use of heat exchanger 138 orthe water heater heat source, the control system continuously assessesthe data sets/COP comparison. If the resulting ratio drops below 1.0,the control system deactivates initially selected heat source andactivates the other heat source. As noted above, system 110 (with heatexchanger 138 active) is generally more efficient than the systemdescribed above with respect to FIG. 2 or FIG. 5, in that reduction offan speed for condenser coil 122 is unnecessary in airconditioning/water heating mode. Counterbalancing that positiveefficiency effect is the longer refrigerant tubing line 131 neededbetween the compressor and the water heater, but this effect is oftenoffset and even overcome by the increase in efficiency caused by thecooling effect the refrigerant experiences as it travels through heatexchanger 138. Accordingly, in most instances, operation of the systemillustrated in FIG. 11 results in a positive system efficiency ratio, ascompared to operation of the system and water heater heat sourceindependently of each other, for a longer rise in temperature of waterin water heater tank 136 than does the systems described above withregard to FIG. 2 and FIG. 5. In addition, since the water heaterreceives hot gaseous refrigerant directly from compressor 126, withoutneed to regulate the refrigerant temperature being directed to the heatexchanger to a lower target temperature, as described above with regardto FIGS. 2 and 5, the heat exchanger illustrated in FIG. 11 can transfermore heat to the water heater, thereby maintaining a positivecontribution to system efficiency over a longer temperature range.Nonetheless, as long as the temperature of refrigerant flowing from thecompressor to heat exchanger 138 is below the water heater's hightemperature set point, the efficiency comparison will eventually favoroperation of the water heater's heat source, causing the system todeactivate water heater heat exchanger 138 and activate the waterheater's inherent heat source. That is, under such circumstances, thewater heater heat source will always bring the water heater water to thefinal high set point, and heat exchanger 138 serves as a pre-heater.Again, however, if the temperature of gaseous refrigerant fromcompressor 126 is at or higher than the water heater high set point, itis possible that heat exchanger 138 can be used to bring the waterheater fully to its high set point.

Electronic control system 120 monitors pressure at the output ofcompressor 12 and, if the monitored pressure exceeds a predeterminedpressure (provided by the compressor manufacturer or by user selection,for example after a calibration process), control system 120 may switchvalve 142 from a closed to an opened state, allowing refrigerant flowthrough a tubing portion 145, bypassing heat exchanger 138 and condensercoil 122, to the lower pressure of the evaporator. In one embodiment,and depending on the compressor capacity, control system 120 mayselectively open proportional valve 142 whenever the compressor outputpressure reaches or exceeds 550 psi. As will be understood in thecontext of the present disclosure, this reduces system efficiency, inthat it diverts heat from transfer to the water heater and reduces theevaporator efficiency, and accordingly valve 142 is metered to minimizeits impact.

If control system 120 changes, either by manual or electronic control,from air cooling to air heating modes, without water heating and withreference to FIG. 10, control system 120 closes valve 154, opens valve144, and sets reversing valve 140 to direct refrigerant flow from tubingline 131 to indoor coil 134 via tubing line 130 and to directrefrigerant flow from coil 122 via line 132 back to compressor 126 viatubing line 132. In operation, hot gaseous refrigerant flows fromcompressor 126 through tubing line 131 and open valve 144, bypassingheat exchanger 138 due to closed valve 154. Reversing valve 140 directsthe gaseous refrigerant to indoor coil 134 via tubing line 130. Coil 134acts as a condenser coil, cooling and condensing the refrigerant toliquid phase as air handler fan 135 moves air over the coils and intothe conditioned space. The re-circulating building air draws heat energyfrom the refrigerant as it condenses, thereby providing a heating effectto the conditioned space. Leaving coil 134 through tubing line 130 (andbypassing expansion valve 160), the now-liquid refrigerant flows to coil122 through expansion valve 163. The expansion valve lowers therefrigerant's pressure, causing outdoor coil 122 to act as anevaporator, in which the refrigerant changes phase to a gas and drawsheat energy from outdoor ambient air drawn over the coils by outdoorunit fan 137. The now-warm gaseous refrigerant flows from coil 122 toreversing valve 140, which directs the refrigerant flow back tocompressor 126 via tubing line 132, and the cycle repeats.

Referring now to FIG. 12, when electronic control system 120 receives asignal from the water heater water temperature sensor (not shown)indicating that the water heater water temperature has fallen below thewater heater's low set point, when the air conditioning system is in airheating mode as discussed above with regard to FIG. 10, control system120 decides whether to activate the heat exchanger or the water heaterheat source, e.g. based on the data sets/COP comparison as describedabove, or by default to the heat exchanger. Assuming the decision is toactivate the heat exchanger, the control system closes valve 144 andopens valve 154, thereby activating heat exchanger 138 by including theheat exchanger and its related portion of tubing section 131 in therefrigerant flow loop. As described above, this causes hot gaseousrefrigerant to flow from compressor 126 to and through heat exchangercoil 138 via tubing section 131 and thereafter to reversing valve 140via check valve 161. The refrigerant's flow from reversing valve 140, toindoor coil 134, expansion valve 163, outdoor coil 122, reversing valve140, and back to compressor 126 occurs as discussed above with regard toFIG. 10.

Again, when electronic control system 120 receives the signal from thewater heater water temperature sensor indicating that water heating isneeded, the electronic control system may initially activate refrigerantheat exchanger 138 rather than the water heater's inherent heat source,when the air conditioning system is operating in either air heating modeor air cooling mode, by default or by the COP comparison. FIGS. 9 and 11illustrate the transition from air cooling-only mode to aircooling/water heating mode, while FIGS. 10 and 12 illustrate thetransition from air heating-only mode to air heating/water heating mode.Continuing the discussion of the latter transition, once the electroniccontrol system has actuated the refrigerant heat exchanger, theelectronic control system thereafter continuously monitors the COPcomparison of system efficiency with operation of refrigerant waterheater 138, and without operation of the water heater's heat source, tosystem efficiency with refrigerant flow heat exchanger 138 deactivatedand the water heater's inherent heat source activated. If this ratiodrops below 1.0 as the system operates, the electronic control systemdeactivates refrigerant flow heat exchanger 138 (by closing valve 154 anopening valve 144), and activates the water heater's inherent heatsource. As in all of the examples described herein, electronic controlsystem 120 continues to monitor the water temperature output signal, andif the ratio rises above 1.0 and persists for a predetermined time willswitch back to activation of the refrigerant flow heat exchanger. Whenthe water heater water temperature rises to the water heater's high setpoint, the water heater heat source may be deactivated by a controlsystem on the water heater that is independent of electronic controlsystem 120, or the heat source may be deactivated by control system 120.As discussed above with regard to air cooling mode, the temperature ofrefrigerant flowing from compressor 126 is also a limiting factor, ascompared to the water heater's high set point. If the compressor'soutput refrigerant temperature is below the water heater's high setpoint, refrigerant flow heat exchanger 138 is always a pre-heatingdevice. If the compressor refrigerant output temperature is higher thanthe water heater high set point, it is possible for refrigerant flowheat exchanger 138 to bring the water heater fully to its high setpoint.

As will be apparent in view of the present disclosure, operation ofrefrigerant flow heat exchanger 138 in an air heating/water heatingmode, as described with regard to FIG. 12, results in the removal ofheat from the refrigerant flow at heat exchanger 138 that mightotherwise be removed at coil 134 for contribution to conditioned air forthe conditioned space. This may result in a reduced system efficiency ascompared to the operation of the system in an air cooling/water heatingmode, thereby resulting in a shorter duration of operation of therefrigerant heat exchanger in air heating/water heating mode than in aair cooling/water heating mode.

Valve 142 is operated by control system 120 in this mode in the samemanner as discussed above with respect to FIGS. 9 and 11.

Referring to FIG. 13, electronic control system 120 receives a signalfrom the water heater water temperature sensor indicating that waterheating is needed, when system 110 is in neither an air heating mode noran air cooling mode, control system 120 sets valves 154, 144, and 140 toan air heating configuration, as discussed above with regard to FIG. 12,but does not activate air handler fan 135 because there is no call fromthe indoor thermostat to provide conditioned air to the conditionedspace. Refrigerant flows through the refrigerant loop as described withregard to FIG. 12.

Again, because refrigerant heat exchanger 138 receives hot refrigerantgas directly from compressor 126, the system's ability to contributeheat to the water heater remains high in this mode of operation.However, the deactivation of air handler fan 135 eliminates thecorresponding air flow over condenser coil 134, thereby reducing thesystem's ability to remove heat from the circulating refrigerant flow.This may undesirably increase pressure at the output of compressor 126.Where compressor 126 is a variable speed compressor, the control systemchanges the compressor's output to a lower level, e.g. 10,000 BTU/hr.Alternatively, electronic control system 120 opens bypass valve 142.This causes hot refrigerant gas from compressor 126 to bypass heatexchanger 138 and coil 134 and flow directly to coil 122 for return tocompressor 126. As described above, the opening of bypass valve 142 mayfurther decrease system efficiency, thereby increasing the likelihood ofa switch to water heater activation.

It should be understood that the present system may be operated invarious manners. For example, as discussed above, each of theembodiments described with regard to FIGS. 1-13 can be operated based ona comparison of system efficiency when using the refrigerant heatexchanger to system efficiency when using the water heater's heatsource, and relying on that comparison as the deciding factor whether toutilize the heat exchanger throughout the water heater's heat cycle.Rather than relying on the efficiency comparison, however, in a furtherembodiment the electronic control system, upon receiving a signal fromthe water heater temperature sensor indicating a need to heat water,actuates the refrigerant heat exchanger coil and maintains the heatexchanger coil active until the temperature signal reaches apredetermined point. This predetermined cut-off point may be determinedthrough testing and comparison of system efficiencies alternativelyutilizing the refrigerant flow heat exchanger and the water heater heatsource. That is, the systems are operated under each of the alternativearrangements, and under similar operating conditions. Systemefficiencies are compared, and a temperature cut off is selected basedon the comparison. Furthermore, temperature may be measured at variouspoints in the water heater, as should be understood in the art, and incertain embodiments the electronic control system responds to watertemperature taken at the lower portion of the lower tank.

Still further, in optional constructions of the air conditioning andwater heating systems described above, the electronically controlledregulator valves may be replaced with fixed orifice solenoid valves, andthe flow of hot refrigerant to the water heater refrigerant-to-waterheat exchanger coils may instead be regulated by compressor discharge(head) pressure using an outdoor or indoor fan speed controller whichis, in turn, controlled by the sensed water temperature in the waterheater tank.

Modifications and variations to the particular embodiments of thepresent invention may be practiced by those of ordinary skill in theart, without departing from the spirit and scope of the presentinvention, which is more particularly set forth in the appended claims.In addition, it should be understood that aspects of the variousembodiments may be interchanged to both in whole or in part.Furthermore, those of ordinary skill in the art will appreciate that theforegoing description is by way of example only and is not intended tolimit the invention so further described in the appended claims.

What is claimed is:
 1. Apparatus for heating water, comprising: a tankfor storing water; a heat exchanger in thermal communication with thetank and configured to receive refrigerant and transfer heat therefromto the tank; an air conditioning system comprising an air handleractuatable to move an air flow through an air flow path into aconditioned space, a refrigerant path having a first portion that passesthrough the air flow path and a second portion that is offset from thefirst portion in the refrigerant path and that passes through the heatexchanger, a pump disposed in the refrigerant path and being actuatableto move refrigerant through the refrigerant path, and a valve systemwithin the refrigerant path that controls refrigerant flow within therefrigerant path, that is selectively configurable to alternativelyallow refrigerant flow through the second portion and bypass refrigerantflow across the second portion, and that is selectively configurablebetween a first state and a second state, wherein the refrigerant pathis configured so that in the first state of the valve system, therefrigerant path flows from the pump, to and through the first portion,then to and through the second portion, and then to the pump, and in thesecond state of the valve system, the refrigerant path flows from thepump, to and through the second portion, then to and through the firstportion, and then to the pump; and a control system comprising at leastone controller in operative communication with the air handler, thevalve system, the pump, and a temperature sensor disposed at theconditioned space that generates a signal corresponding to a temperatureof the conditioned space and in response to which the control system isconfigured to actuate and deactuate the air conditioning system, and acomputer-readable medium containing program instructions executable bythe at least one controller to control actuation of the air handler, thevalve system, and the pump, wherein the control system is incommunication with the valve system to selectively move the valve systemfrom one of the first state and the second state to the other of thefirst state and the second state, and wherein the program instructionsare configured so that the control system, in a first mode of operation,actuates the air handler to move the air flow through the air flow pathand actuates the pump and the valve system to move refrigerant throughthe first portion of the refrigerant path and the second portion of therefrigerant path, and in a second mode of operation, maintains the airhandler in an inactive state and actuates the pump and the valve systemto move refrigerant through the first portion of the refrigerant pathand the second portion of the refrigerant path.
 2. The apparatus as inclaim 1, wherein the control system includes a thermostat that includesthe temperature sensor and that is operable in response thereto to senda first signal to the at least one controller providing instructions tothe at least one controller to actuate and deactuate the airconditioning system, and wherein the at least one controller actuates ordeactuates the air conditioning system in response to the first signal.3. The apparatus as in claim 2, wherein the control system is inoperative communication with the valve system to selectively configurethe valve system to allow refrigerant flow through the second portion orbypass refrigerant flow across the second portion.
 4. The apparatus asin claim 2, wherein the air conditioning system includes a temperaturesensor in thermal communication with water in the tank and incommunication with the control system to send a second signal to thecontrol system corresponding to a temperature of the water in the tank,and wherein the control system is configured to control the valve systemto allow refrigerant flow through the second portion or bypassrefrigerant flow across the second portion, in response to the secondsignal.
 5. The apparatus as in claim 2, wherein the first portion of therefrigerant path includes a first coil disposed in the air flow path andthe refrigerant path includes a second coil.
 6. The apparatus as inclaim 5, wherein the air conditioning system includes a fan proximatethe second coil so that operation of the fan moves an air flow acrossthe second coil.
 7. The apparatus as in claim 5, wherein the refrigerantpath is configured so that in the first state of the valve system, therefrigerant path flows from the pump, to and through the first coil,then to and through the second portion, then to and through the secondcoil, and then to the pump, and in the second state of the valve system,the refrigerant path flows from the pump, to and through the secondcoil, then to and through the second portion, then to and through thefirst coil, and then to the pump.
 8. The apparatus as in claim 7,wherein the refrigerant path includes a first bypass path fluidly acrossthe first coil and a second bypass path fluidly across the second coil.9. The apparatus as in claim 8, wherein the valve system includes afirst valve in the first bypass path that is selectively configurable toalternatively block and allow refrigerant flow through the first bypasspath, the valve system includes a second valve in the second bypass paththat is selectively configurable to alternatively block and allowrefrigerant flow through the second bypass path, and the control systemis in operative communication with the first valve and the second valveto respectively control the first and second valves to allow or blockrefrigerant flow in the valves' respective bypass paths.
 10. Theapparatus as in claim 9, wherein the control system is configured toconfigure the first valve to allow refrigerant flow through the firstbypass path when the valve system is in the first state, and wherein thecontrol system is configured to configure the second valve to allowrefrigerant flow through the second bypass path when the valve system isin the second state.
 11. The apparatus as in claim 1, wherein in a thirdmode of operation, the control system actuates the air handler to movethe air flow through the air flow path, actuates the pump to moverefrigerant through the first portion of the refrigerant path and setsthe valve system to bypass refrigerant flow across the second portion ofthe refrigerant path.
 12. An apparatus for heating water, comprising: atank for storing water and including a temperature sensor in thermalcommunication with water in the tank and operable to output a firstsignal corresponding to a temperature of the water in the tank; a heatexchanger in thermal communication with the tank and configured toreceive refrigerant and transfer heat therefrom to the tank; an airconditioning system comprising an air handler actuatable to move an airflow through an air flow path into a conditioned space, a refrigerantpath having a first portion that passes through the air flow path and asecond portion that passes through the heat exchanger, a pump disposedin the refrigerant path and being actuatable to move refrigerant throughthe refrigerant path, a valve system within the refrigerant path thatcontrols refrigerant flow to the first portion and the second portion,that is selectively configurable to alternatively allow refrigerant flowthrough the second portion and block refrigerant flow through the secondportion, and that is selectively configurable between a first state anda second state, wherein the refrigerant path is configured so that inthe first state of the valve system, the refrigerant path flows from thepump, to and through the first portion, then to and through the secondportion, and then to the pump, and in the second state of the valvesystem, the refrigerant path flows from the pump, to and through thesecond portion, then to and through the first portion, and then to thepump, and a thermostat operable to measure ambient temperature in theconditioned space and to output a second signal corresponding to ambienttemperature in the conditioned space; and a control system comprising atleast one controller in operative communication with the tank to receivethe first signal, in operative communication with the thermostat toreceive the second signal, in operative communication with the airhandler, in operative communication with the pump, and in operativecommunication with the valve system, and a computer-readable mediumcontaining program instructions executable by the at least onecontroller to control actuation of the air handler, to control actuationof the pump, and to control the valve system to selectively allowrefrigerant flow through the second portion and block refrigerant flowthrough the second portion, wherein the control system is incommunication with the valve system to selectively move the valve systemfrom one of the first state and the second state to the other of thefirst state and the second state, and wherein, the program instructionsare configured so that the control system, in response to the firstsignal and the second signal, in a first mode of operation, actuates theair handler to move the air flow through the air flow path and actuatesthe pump and the valve system to move refrigerant through the firstportion and allow refrigerant flow through the second portion, in asecond mode of operation, maintains the air handler in an inactive stateand actuates the pump and the valve system to move refrigerant throughthe first portion and allow refrigerant flow through the second portion,and in a third mode of operation, actuates the air handler to move theair flow through the air flow path and actuates the pump and the valvesystem to move refrigerant through the first portion and blockrefrigerant flow through the second portion.
 13. The apparatus as inclaim 1, wherein the control system includes a thermostat that includesthe temperature sensor and that is operable in response thereto to senda first signal to the at least one controller providing instructions tothe at least one controller to actuate and deactuate the airconditioning system, the at least one controller actuates or deactuatesthe air conditioning system in response to the first signal, the airconditioning system includes a temperature sensor in thermalcommunication with water in the tank and in communication with thecontrol system to send a second signal to the control systemcorresponding to temperature of the water in the tank, and the programinstructions are configured so that the control system implements thesecond mode of operation based at least upon indication by the firstsignal of an instruction to activate the air conditioning system toprovide conditioned air to the conditioned space, and indication by thesecond signal that the temperature of the water in the tank is below apredetermined threshold.
 14. The apparatus as in claim 1, wherein theair conditioning system includes a second heat exchanger in therefrigerant path.
 15. The apparatus as in claim 14, wherein, in thesecond mode of operation, the refrigerant path is arranged so thatrefrigerant flows from the pump to the second heat exchanger so thatrefrigerant flows through the heat exchanger and the first portionbefore reaching the second heat exchanger and through an expansion valveafter flowing through the first portion and upstream of the second heatexchanger.